Attitude And Orbit Coupled Tracking Control For Spacecraft Relative Motion

With the diversification and complication of space mission, autonomous on-orbit servicing technology emerges as the times require, while the autonomous rendezvous and docking to the target spacecraft is the basis for close-range servicing operations. Aiming at the coupled control problem during the rendezvous and docking to an out-of-control and free tumbling target, this dissertation investigates an attitude and orbit integrated modeling method of relative motion and designs corresponding integrated control algorithms,The main contents are as follows:The concept of dual quaternion is introduced. Then the dynamic model of six degrees of freedom for a single spacecraft is established by using dual quaternion, and based on this, an integrated dynamic model of relative motion between two spacecraft is established. The source of the coupling terms is analyzed.A PD-like controller is designed, and the system proved to be globally asymptotically stable by using Lyapunov method and Barbalat lemma. Through the simulation comparison with PD control based on log feedback, the proposed method shows better dynamic performance and saves energy. The dynamic performance of the position part is improved and the energy consumption is further reduced by using fuzzy control to improve the PD controller. The robustness of the controllers is verified by adding uncertainty of mass and inertial moment into numerical simulations.By changing dual quaternion multiplication, a cascade active disturbance rejection controller is designed. By designing the virtual controller and the error feedback control law,and using tracking differentiator to arrange the transient process, the controller achieves good tracking performance when disturbances are small. The total disturbance can be estimated by extended state observer, and then it can be compensated. The robustness of the designed controller is verified.In order to reduce adjustable parameters of the controller to improve practicality, a robust control law is designed based on input-to-state stability(ISS) theory. The closed-loop system is exponentially stable when disturbances vanish, and is locally input-to-state stable when bounded disturbances exist. Simulation results show that the system has smooth transition process and high accuracy when disturbances increase, which means that the control system has strong robustness.